Every morning, 13-year-old Marcelo Jesus Gouriyú and his nine-year-old brother leave their home in the small Venezuelan town of Calié at half past four in the morning to go to school in Colombia.

The two children walk unaccompanied through the dark for around two hours to make it in time for the start of their lessons at half past six.

As the sun rises, they slip into Colombia through informal border crossings known as trochas to reach their school in the town of Paraguachón.

The trochas in this region on Colombia's northern tip are dangerous rural dirt tracks that weave across the arid border and are controlled by local armed groups, which often charge users a fee to pass through.

In what may well be a sign of teenage bravado, Marcelo denies being scared of journeying through these informal crossings day in day out.

"I like coming to school in Colombia," he says, adding that "they don't really have lessons there [where I live]".

Venezuela's crumbling economy and ongoing socio-political crisis has pushed many institutions to the brink.